Grape seed procyanidins PC are flavan-3-ol oligomers and polymers known for their biological activity in the gut. Grape seed extract GSE have been reported to reduce intestinal injury in a rat model of mucositis. We sought to investigate effects of purified PC fractions differing in mean degree of polymerization mDP combined with 5-Fluorouracil 5-FU chemotherapy on the viability of colon cancer cells Caco-2.

PCs of mDP 2–6 immature F1-F3 and mature F1 and F4not only enhanced the impact of 5-FU in killing Caco-2 cells, but also surpassed standard 5-FU chemotherapy as an anti-cancer agent.The bioactivity of PC is therefore attributed primarily to lower molecular weight PCs.